1. Technical Field
The present invention relates to a paper conveyance device for recording media on which information is recorded, and to a printer having the paper conveyance device.
The present application claims priority based on and incorporates by reference the entire contents of Japanese Patent Application No. 2010-202774 filed in Japan on Sep. 10, 2010, and No. 2010-202775 filed on Sep. 10, 2010.
2. Related Art
Printers are used for recording information in business and many other fields. As a result, many different kinds of recording media are also used for recording information. These recording media include multipart forms composed of plural sheets. This type of recording medium is typically supplied as fanfold paper. Fanfold paper has sprocket holes (conveyance holes) formed in the conveyance direction, is perforated between each page so that the pages can be easily separated, and is stored in a stack with the pages alternately folded in opposite directions at the perforations. Fanfold paper is conveyed by a paper conveyance mechanism with a tractor.
The tractor has tractor pins that can be inserted in the sprocket holes of the fanfold paper, and a tractor belt having the tractor pins formed with a specific interval therebetween on the outside surface. The fanfold paper is set so that the tractor pins are inserted in the sprocket holes. The tractor causes the tractor belt to turn by means of drive power from a drive source, and conveys the continuous paper while causing the tractor pins to sequentially engage the sprocket holes of the continuous paper. See, for example, Japanese Unexamined Patent Appl. Pub. JP-A-2006-232470.
The paper conveyance device of a business printer that records information on continuous paper has a paper feed roller and a pressure roller near the printhead in addition to the tractor described above, and feeds the continuous paper in increments of a specific feed distance by synchronously driving the paper feed roller and the tractor See, for example, Japanese Unexamined Patent Appl. Pub. JP-A-2009-119574.
Printers record information on a conveyed recording medium using a printhead. To achieve better print quality, the recording medium must be conveyed appropriately. If the conveyed recording medium is wrinkled or puckered (does not lie flat), a desirable relationship between the printhead and the recording medium is not maintained and print quality may suffer. To prevent wrinkles and bulges in the recording medium, Japanese Unexamined Patent Appl. Pub. JP-A-H09-48161 teaches an inkjet printer that creates lands and grooves by means of ribs throughout the recording medium conveyance path, and corrects bulging and separation of the recording medium from the platen.
There are now many different types of recording media and many different types of printers. When the recording medium is a multipart form having plural sheets with adhesive applied along both edges in the conveyance direction, the sheets can contract and wrinkle due to humidity and other environmental effects. When multiple sheets of different materials are combined, the sheets contract at different rates and one sheet may wrinkle much more than the other. When printing to such recording media with a printer such as an inkjet printer, an appropriate gap cannot be maintained between the printhead and the recording medium, and print quality drops. In extreme cases the recording medium may touch the printhead, and normal printing may not be possible. In addition, when a paper feed mechanism with rollers is disposed near the printhead and the pressure roller is used to correct such problems, the roller may crush the wrinkled part and create a creased wrinkle.
The inkjet printer that corrects paper wrinkles by means of full-surface ribs as taught in JP-A-H09-48161 describes correcting wrinkles in single-sheet paper, and is silent regarding correcting the severe wrinkles and media bubbles that can occur when plural sheets are combined in a multipart form as in the recording medium described above.